The purpose of this research is to study some basic auditory factors that may affect speech reception by hearing-impaired persons under noisy reverberant conditions. The auditory factors are: 1) the echo-integrating capacity of the auditory system and 2) the spatial, separating function of the binaural system. Echo integration refers to the known capacity of the auditory system to summate, for perceptual purposes, a direct speech signal and an echoed (delayed) version of the same signal. The binaural aspect of hearing also enhances speech reception in noisy rooms and may interact with echo integration. We propose to investigate how echo integration and binaural hearing together affect speech reception. Speech reception tests will be carried out in rooms with variable reverberation and also under controlled echo conditions simulated by a computer. Various speech-to- noise ratios will be used and the tests will be carried out both monaurally and binaurally. Noises will be: 1) a voice babble and 2) impulse noise. Tests will be performed on normal listeners and on listeners with sensorineural impairment of hearing who are wearing hearing aids. Normal listeners will be tested both with and without hearing aids. Normal and impaired results will be compared. We expect the results to have important implications for auditory theory, for the acoustic design of rooms, and for the use of hearing aids.